- Apodia 755.31
- Apophysitis (bone) (see also Osteochondrosis) 732.9
- Apoplectiform convulsions (see also Disease, cerebrovascular, acute) 436
- Apoplexia, apoplexy, apoplectic (see also Disease, cerebrovascular, acute) 436
- Appendage
- Appendicitis 541
- Appendiclausis 543.9
- Appendicolithiasis 543.9
- Appendicopathia oxyurica 127.4
- Appendix, appendicular - see also condition
- Appetite
- Apprehension, apprehensiveness (abnormal) (state) 300.00
- Approximal wear 521.10
- Apraxia (classic) (ideational) (ideokinetic) (ideomotor) (motor) 784.69
- Aptyalism 527.7
- Aqueous misdirection 365.83
- Arabicum elephantiasis (see also Infestation, filarial) 125.9
- Arachnidism 989.5
- Arachnitis - see Meningitis
- Arachnodactyly 759.82
- Arachnoidism 989.5
- Arachnoiditis (acute) (adhesive) (basic) (brain) (cerebrospinal) (chiasmal) (chronic) (spinal) (see also Meningitis) 322.9
